Involvement of prolyl endopeptidase in ascidian fertilization

Summary Inhibitory effects on fertilization of the ascidian of three benzyloxycarbonyl(Z)-aminoacyl prolinals and Z-Gly-Pro-chloromethyl ketone added before and after insemination were examined. The results suggest that the prolyl endopeptidase is involved in the process of fertilization, especially in a process taking place between chorion elevation and cell cleavage.Acknowledgment. We are indebted to Dr T. Numakunai of the Marine Biological Station of Tohoku University for collecting the ascidians and to Dr M. Hoshi of the Tokyo Institute of Technology for his helpful discussion. We are also grateful to Dr T. Yoshimoto and Prof. D. Tsuru of Nagasaki University for their generous gift of Z-Gly-Prochloromethyl ketone. This work was supported by a Grant-in-Aid from the Ministry of Education, Science and Culture of Japan.